Deere 420 belly mower slow to engage. Problem somewhere on engine

MilesToEmpty

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  • / Deere 420 belly mower slow to engage. Problem somewhere on engine
Two days ago I was mowing our back field and hit a piece of a 4"x4" piece of wood. No clue where it came from.

Anyway, I got it on the left blade and it jammed the deck instantlly. The whole mower stalled out on it.

Restarted the engine and drove to the garage to see the damage. Unjammed the deck, and it spins freely.

However, it doesnt engage properly now. On the front of the engine there are 3 pullies.
Pully on the engine crank
Idler Pully
PTO Pully

You can spin them by hand, so I know nothing is bent or broken, however when you engage the deck, it seems lie its extremely slow to engage. Or it just wont. You hear the engine start making "puffing" noises as the deck spools up (if the deck starts).

It will only start up if the engine is at the lowest rpm possible. If you start it at full RPM it barely spins the blades on the deck.

Im pretty sure the problem is on the engine crank pully. But Im not sure how it really works. If there's a clutch there, I think its gone.

Looking for some suggestions.
 

KennyV

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  • / Deere 420 belly mower slow to engage. Problem somewhere on engine
you should never engage any pto at full RPM... (I know you can get buy doing it ... for a while)... you can also slide your transmission into drive while holding the accelerator to the floor... but it's not a good idea.

Is the belt on the pulleys?
Is the tension on the belt OK?
Is the deck pulley slipping on the spindle?

If these check out.. can turn the clutch pulley (with the pto switch on) Engine not running... If the clutch is slipping you will need to look further at the clutch... :smile:KennyV
 

MilesToEmpty

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  • / Deere 420 belly mower slow to engage. Problem somewhere on engine
I was always told to engage the mower deck at the operating rpm. That's actually what our Deere dealer told us to do. But seeing as they have serviced our 420 riding mower once and will never again, I will do as you suggest.

Both belts are brand new. As us the idler. The tension is as specified by Deere.

You can turn the deck if you rotate by hand the pulleys on the front of the mower.

Engaging the mower deck, you hear what sounds like an air Pump that is puffing faster as the deck starts up. However it will never fully get to speed. If you kick it on at a high rpm you will hear this puffing but the pullies on the front of the engine won't really start up.

Again you can easily turn them all by hand, so there is nothing straining the deck from starting.

I think the problem is within the clutch of a pulley somewhere.
 
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MilesToEmpty

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  • / Deere 420 belly mower slow to engage. Problem somewhere on engine
The more I think about it, I feel like the pto clutch is gone.
 

MilesToEmpty

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  • / Deere 420 belly mower slow to engage. Problem somewhere on engine
This is the area where I think the issue is:
DSC01551.jpg

DSC01552.jpg

DSC01554.jpg
 

KennyV

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  • / Deere 420 belly mower slow to engage. Problem somewhere on engine
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